Mobil Oil Corporation

Wilton Gravley

Thomas B Dellinger

James H Sexton

Bobbie J Patton

C Mackay Foster, Jr

John E Walraven

Directional drilling is carried out with a rotary drilling tool having a drill string, a drill bit, a drill motor for rotating the drill bit independently of the drill string, and a bent sub affixed between the lower end of the drill string and the drill motor for angularly displacing the axis of rotation of the drill bit from the axis of rotation of the drill string. Both the drill string and drill bit are rotated to provide a straight path for the wellbore, while only the drill bit is rotated during the deviation of the wellbore from a straight path.

System of drilling deviated wellbores

This specification discloses a rotary drilling technique for drilling a highy deviated wellbore into the earth's crust wherein a drill string comprised of drill collars and drill pipe is used to advance a drill bit attached to the drill pipe at the lower end of the drill string into the earth and form the wellbore. A first portion of the wellbore is formed to extend into the earth's crust and thereafter a highly deviated second portion of the wellbore is formed by drilling with the drill string arranged to have the drill collars located in the first portion of the wellbore and to apply compressive force on the drill pipe that extends therebelow and thus on the drill bit attached to the lower end thereof to apply the desired weight-on-bit for effective drilling of the second portion of the wellbore.

Extended reach drilling method

In the drilling of a well, buckling of a drill string is prevented by determining the buoyed weight, sliding friction, and external forces applied to the segments of a drill string and comparing the resultant axial force on each segment with a buckling threshold to indicate when the resultant axial force exceeds the threshold. The azimuth and inclination of segments of the drill string are measured. The forces on the drill string are resolved into the axial and normal components applied to the next shallower segment. From these, the forces applied to each segment are determined.

Preventing buckling in drill string

A rotary method and arrangement mitigate differential sticking of a drill string during the drilling of a wellbore and for improving cuttings removal. Tool joints are used for interconnecting joints of drill pipe together into a drill string for use in drilling the wellbore. Nozzles are provided in the tool joints or drill pipe to cause a flow of drilling fluid into the wellbore from the interior of the drill string during the drilling operation to improve removal of the cuttings from the wellbore and mitigate differential sticking of the drill string.

Method and arrangement for improving cuttings removal and reducing

In a well drilling system, a drill bit is raised or lowered through formations surrounding a borehole in response to the movement of a cable onto and off of a drawworks drum. Magnetic markings are affixed to the drum, and a pair of sensors detect rotational movement of the magnetic markings as the drum rotates to take in or pay out the cable. These sensors provide signals indicating both the direction and magnitude of drum rotation. These signals are digitized and selectively gated to operate a bidirectional counter whose count output is recorded as a function of time to provide a depth recording indicating penetration of the drill bit through the formations surrounding the borehole.

Well drilling system

In a well drilling system, a drill bit is raised or lowered through formations surrounding a borehole in a response to the movement of a cable onto and off the drawworks drum. Prior to drilling operations, the drilling system is calibrated by lowering the traveling block to its lowest position above the rig floor. At this position, the distance from a predetermined reference point to the traveling block is measured as is the rotational position of the drawworks drum. Cabling is then taken into the drum until one full layering of cable is wound onto the drum. At this time, the distance from the fixed reference point to the new position of the traveling block is measured as is the amount of rotation of the drum required to move the traveling block to this position. These steps are repeated for each full layering of cable to be wound onto the drum before the traveling block reaches its maximum distance above the reference point to determine the amount of rotation required to move the traveling block the distances to the new positions. During drilling operations, the position of the traveling block in any given time is determined for any cable layering in accordance with a predetermined relationship between the measurements made during the calibration period.

Growing community of inventors

Carrollton, TX, United States of America

Wilton Gravley